Radiocircuit



R. BOWN.

RADIOCIRCUITS.

APPLICATION HLED JULY 2,1921.

1 8 599, mm m 311 1922.

nu M4 606 @2913 abtowm sary in the Patented @ct. 3i, I22.

RALPH BOWN, OF EAST ORANGE, NEW JERSEY,

ASSIGNOR TO AMERICA! TELEPHONE AND TELEGRAPH COMPANY, A CURPORATION NEW YORK.

RADIOCIRCUI'I.

Application filed July 2,

To all whom it may concern:

Be it known that I, RALPH BOWN, residing at East Orange, in the county of Essex, and State of New Jersey, have invented certain Improvements in Radiocircuits, of which the following is a specification.

This invention relates to signaling circuits, and more particularly to signaling circuits of the radio type.

Where it is desired to simultaneously send and receive in a radio system, as is necescase of radio telephony, it has been customary to separate the oppositely directed transmission by employing some or all of the following principles: (a) separation b s'electivit ,that is, the employment of di erent carriers for transmittingand receiving; (6) separation by balance,that is, the transmitting circuit'is rendered at least partially conjugate with respect to the receiving circuit; (0) by geographically separating the transmitting and receiving antenna of a particular station, so that the sending energy from the transmitting antenna will produce a minimum effect upon the receiving antenna.

For the most eflicient operation, all three of these principles should bSeinployed simultaneously. .This is usually possible in case of a shore station. In the case of a ship set, however, geographical separation of the sending and receiving antennae is impossible, and it has been customary, therefore, to rely entirely upon separation by selectivity and balance. a

In accordance with the present invention it is proposed to introduce another ethod of separation in which difi'erentiatio between the sending and receiving channels will be obtained upon a time basis by associating the sending and receiving radio channels alternately with the local low frequency line or other type of signaling circuit. Preferably, this switching may take place at a frequency higher than the signaling frequencies and lower than the radio frequencies involved. As a means for controlling the commutating or switching operation, advantage is taken of the switching function of a vacuum tube, which has the desirable characteristic of substantial absence of inertia as compared with mechanical switching means.

In considering a pair of interconnecting radio stations, it is desirable to apply the I Sity 7 radio system 1921. Serial no. teams.

method of high frequency switching or commutating to but one of the stations, as, for example, to a ship station, for it will usually be found hat at one of the stations equivalent results may be obtained by separating the receiving and transmitting antennw. By' applying the scheme to .but one of the interconnecting stations, the necesof commutating at a plurality of stations in synchronism is obviated.

In general, the commutating or switching operation may take place at three difierent points, (a) in the audio frequency part of the system before modulation in the transmitting channel and after demodulation in the receiving channel; (1)) in the radio frequency part of the system after modulation in the transmitting channel and before demodulation in the receiving channel, and (c) in the circuits leading to the carrier frequency source for supplying the modulator and demodulator.

The invention may derstood from the following description, when read in connection with the accom panying drawings, Figures 1, 2 and 3 of which illustrate the circuit arrangements embod'yin the three different methods of commutating, just referred to.

Referring to Fig. 1, L designates a low frequency signaling circuitsuch as a tele-' phone line associated with the transmitting channel Till and receiving channel RIi'of a through a hybrid coil 10, similar to that used in connection with telephone repeaters. The line L is balanced at low frequencies by means of or artificial line N, so that, as regards low frequencies, the transmitting and receiving channels TL and RL may be rendered conjugate. A modulator M, which may be of the well-known vacuum tube type, is included in the transmitting channel TL between the connection of the channel with the line L and the transmitting antenna TA. The modulator M may be supplied with carrier currents of radio frequency from a suitable source S. The receiving channel RL includes a detector or demodulator D, which may be of the well-known vacuum tube type. While this detector may be supplied with a locally enerated'carrier fro uency for beating witg the received signal and in accordance with the homodyne method of receivng, as here shown, the detector is of the now be more fully una suitable network;

simple non-homodyne type employed where will at the same moment have a pulse of the carrier frequency is radiated with the current supplied to its grid, of such a charside bands. The input circuit of the deacter as to prevent transmission. The next tector is associated with the receiving an succeeding half-wave will be in the opposite tenna RA. 7 direction, however, and will shift the oper- In case the receiving antenna is not ating point of thetube RI to the amplifying screened against energy from the transmitportion of its characteristic, so that the reting antenna TA, it will be apparent that ceived radio oscillations will be free to be a singing circuit will be established somepassed through the interrupter and 1mwhat analogous to that of a 22 repeater cirpressed upon the detector D. Transmitting cuit from the antenna TA to the antenna and receiving will, therefore, take place al- RA through the detector D of the receiving ternately at a high frequency rate deterchannel RL, through the partially unbalmined by the frequency of the oscillator O. anced hybrid coil 10 into the transmitting This frequency, as previously stated, should channel TL and through the modulator M preferably be above audibility and below back to the transmitting antenna. Singing the frequency of the carrier-employed for of this character may be prevented, however, radio signaling. by alternately rendering the transmitting Instead of including commutating or inand receiving channels inoperative at a rate terrupting devices at the points indicated in sufliciently high to be above audibility, yet Fig. 1', these devices may be included in the sufficiently low to permit free transmission carrier supply source as indicated in Fig. 2. of the radio frequency during the operative In this case, the transmitting interrupter interval of the channel. In order to render TI, which is in all respects similar to the the two channels alternately inoperative, a interrupter TI of Fig. 1, is interposed 'betransmitting interrupter TI is interposed tween the radio fre uency carrier-source S between the modulator M and the transmitand the modulator ,so that the carrier freting antenna TA of the transmitting chanquency is applied to the modulator at sucnel and a similar interrupter BI is intercessive intervals each time an alternation of posed between the receiving antenna RA the proper sign is applied to the device TI and the detector D of the receiving channel. to render the same operative. The receiving These interrupters constitute vacuum tubes interrupter RI will be connected between having their grid circuits normally provided the detector and the carrier source, regardwith static potentials of such polarity and less of whether the source is supplied locally value that the tubes will not transmit curor is transmitted from the distant sending rents unless the static potential on the grid station. In the latter case, since the carrier is changed. is received by the antenna-,iR-A and. applied In order to alternately change the static fromthe antenna to the detector D, the regrid potentialsof the two interrupters TI ceiving interrupter RI, which is in all reand RI, a source of alternating current 0 spects similar to the corresponding device is provided. This alternating current source of Fig. 1, will be included directly between may be, for example, the well-known vacthe receiving antenna RA and the detecting uum tube oscillator. The alternating curtube. The arrangement of the devices TI rent from this oscillator may be passed and BI is such that they will be operative through a distortingtube DT of the wellalternately, as described in connection with known type which is so arranged as to ren- Fig. 1, and hence the station will alternately 11( der the alternating waves supplied'by the transmit and receive at a frequency deteroscillator flat topped. These fiat topped almined by the oscillator O. ternating waves are supplied to the grid cir- The commutating devices TI and RI may cuits of the interrupters TI and RI through also be included in the low frequency part suitable phase shifters 11 and 12. By propof the circuit, as illustrated in Fig. 3. In erly connecting the circuits and adjusting this case, the transmitting interrupting tube these phase shifters, the alternating wave TI is connected between the input of the may be caused to produce opposite effects modulator M and the connectionlof the simultaneously upon the two interrupters transmitting channel TL to the ow fre- TI and RI, so that when one is rendered quency line, so that the signaling currents 12 operative, the other will be inoperative. For are applied to the modulator at successive example, if a wave of proper polarity is high frequency intervals determined by the superposed on the normal potential in the oscillator O. The receiving interrupter or grid circuit of the tube TI, the tube may be commutator RI is included between the outcaused to operate upon the straight ampliput circuit of the detector D and the con- 12 fying portion of its characteristic during nection of the receiving channel BL with the flat topped interval of the supplied wave the line L. The detected low frequency curso that the modulated radio frequency will rents applied in the output circuit of the debe freely transmitted through the intertector D will, therefore, be interruptedly rupter TI to the antenna TA. The tube RI supplied during successive intervals, deter- 12 mined by the oscillator U, to the line h. before, the interruptions in the transmitt' a recei chaninalsv take place alternately, so that the station will. successivel transmit and receive at a frequency depen out upon the irequenc of the oscillator '0. lit willbe obvious t at the general prin ciples herein disclosed may be embodied in many other organizations widely different In those illustrated, without departing from the spirit of the invention as defined in the folhiwing claims.

What is claimed is:

1. ln aradio signaling system, a transmitting antenna and a receiving antenna, transmitting apparatus. associated with said transmitting antenna, said tranmnitting apparatus comprising a source of signaling current and a source of carrier current, a

vacuum tube commutator included between the transmitting antenna and one of said sources, receiving apparatus associated with the receiving antenna comprising circuits for translating received radio frequencies into low trequencysignals, a vacuum tube commutator included in said receiving ap-' paratus, and means for causing said cornmutators associated with the transmitting and receiving apparatus to commutate ,alternately. a

2. In a radio signaling system, atransmit.

ting antenna and mitting apparatus associ transmitting antenna, said vtransmitting apparatus comprising a source of signaling current and a source of carrier current, a vacuum tube commutator included between the transmitting antenna and one of said sources, receiving apparatus associated with the receivin for translatlng received radio frequencies into low frequency signals, a vacuum tube commutator included in said receiving apparatus, and a source of alternating current for supplying said vacuum tube commutators, said source rendering said transmitting and receiving commutators alternately operatlve.

3. In a radio signaling system, a transmita receiving antenna, transated with said ting antenna and 'a receivmg antenna, transmitting apparatus associated with 'said transmitting antenna, said transmitting apparatus comprising a source of signaling current'and a source of carrier current, a commutator operating without mechanical inertia included between the transmitting antenna and one of said sources, receiving apparatus associated with the receiving antenna comprising circuits for translating received radio frequencies into low frequency signals, a commutator operating Without mechanical inertia included in said receivantenna comprising circuits As ing apparatus, and means for commutator-s associated with ting and recei alternately.

causing said the transmitvlng apparatus to commutate tt i. In a radio signaling system, a transmitting antenna a low Knitting low frequency frequency signaling circuit,

channel interconnecting said low fi'equency circuit and a receiving channel inertia included in said and a receiving antenna,

a trans- 7t transmitting antenna inter-connecting said circuit and receiving antenna,

commutators operating without mechanical trmitting and receiving channels, and means to cause said commutators to commutate 5. In a rad mitting antenna, a frequency signaling circuit, a transmitting interconnecting said low frequency signaling circuit and said tenna, a receiving said low frequency antenna, vacuum tube commutators included in said transmitting and receiving channels,

a respectively, and V uum tube commutatorsoperative alternately.

6. In a signaling antenna, a receiving antenna and a low frequency signaling channel interconnecting said low signaling circuit and said transmitting channel terms, a recei said low frequency signaling circuit said receiving mutating ternatcly mutators.

antenna, a

channel interc signaling circuit and tenna, a recei said low freq said receiving mutating devi ting and recei tube commutators, said connections being so arranged that sign will render one of operative, and opposite sign June 1921.

devices included in said mitting and receiving channels, respectively, and a source of energizing said vacuum tube com- 7. In a signaling system, a transmitting receiving antenna, a low frequency signaling circuit, a transmitting ernating current and connecalternately.

io signaling system, a transreceiving antenna, a low transmitting anchannel interconnecting circuit and said receiving means to render said vacsystem, a transmitting circuit, a transmitting frequency ving channel interconnecting with e comtransantenna, vacuum tub alternatln current for allllll onnecting said low frequency said transmitting anving channel interconnecting uency signaling circuit with antenna, vacuum tube comces included in said transmitving channels, respectively, a

an alternating impulse of one said commutators an alternating impulse of the will render the other commuwhereof, I have signed my is 30th day'of nnnrn sown. 

